Federal workers are spraying a weed-killer in the Los Angeles River a state agency recently labeled as carcinogenic.

At issue is the chemical glyphosate, the active ingredient in Roundup, an herbicide used frequently in agriculture and as well as by homeowners, U.S. Rep. Adam Schiff, D-Burbank said. Last summer, the state placed glyphosate on a list of chemicals linked to cancer and birth defects.

In addition, a study published in November in the Journal of the National Cancer Institute concluded there is a possible association between glyphosate and acute myeloid leukemia, a form of blood cancer.

The U.S. Army Corps of Engineers, which maintains the 51-mile Los Angeles River and is working with the city of Los Angeles on its restoration, should take a cue from local and state agencies, Schiff said.

“The predominant concern is it could pose a heath risk to people who live near the river,” Schiff said in an interview Thursday. “But it is very detrimental to wildlife in the river, so there are also environmental concerns.”

In a letter released last week, Schiff asked Col. Kirk E. Gibbs, district commander of the Los Angeles District Army Corps, to “end its use of products containing glyphosate as part of the (Los Angeles River) vegetation management plan in favor of safe alternatives.”

As of late Thursday, the congressman said he had received no response. If the Army Corps does not comply, Schiff will consider proposing legislation or cuts to the agency’s funding, he said.

Army Corps spokesman Jay Fields confirmed his agency has received the congressman’s letter and is preparing a response. He added the Army Corps is testing new methods for weed control without glyphosate.

Members of Friends of the Los Angeles River and residents in Atwater Village and Elysian Valley have expressed concerns about the use of the herbicide in the river that runs adjacent to their neighborhoods, Schiff said.

“We are making the case for other alternatives for vegetation management,” said Michael Atkins, spokesman for the group. The group is in support of Schiff’s demand.

But there remains disagreement among health agencies over the health risks associated with the chemical.

In 2015, the World Health Organization classified glyphosate as “probably carcinogenic in humans.” But the European Food Safety Authority concluded the chemical is not likely to damage DNA and is an unlikely carcinogenic threat.

In December, the U.S. Environmental Protection Agency said in a draft risk assessment that the chemical is not likely carcinogenic, contradicting the World Health Organization and the state Office of Environmental Health Hazard Assessment. The latter agency put the chemical on the list of others known to cause cancer in adherence to Proposition 65, a ballot measure passed in 1986 requiring listing of toxic chemicals used in the state.

Monsanto, the chemical giant that makes Roundup, requested the state reconsider its listing but was rejected last summer. The chemical company argued that the Agricultural Health Study — a query into the health of pesticide users and their families in two states by four federal agencies — found no evidence of any association between glyphosate exposure and non-Hodgkin lymphoma, a type of cancer, according to a petition filed with the state.

The herbicide is safe and has been used for 40 years, according to Monsanto’s website. Company representatives did not return multiple requests for comment.

Steve Scauzillo covers environment and transportation for the Southern California News Group. He has won two journalist of the year awards from the Angeles Chapter of the Sierra Club and is a recipient of the Aldo Leopold Award for Distinguished Editorial Writing on environmental issues. Steve studied biology/chemistry when attending East Meadow High School and Nassau College in New York (he actually loved botany!) and then majored in social ecology at UCI until switching to journalism. He also earned a master's degree in media from Cal State Fullerton. He has been an adjunct professor since 2005. Steve likes to take the train, subway and bicycle – sometimes all three – to assignments and the newsroom. He is married to Karen E. Klein, a former journalist with Los Angeles Daily News, L.A. Times, Bloomberg and the San Fernando Valley Business Journal and now vice president of content management for a bank. They have two grown sons, Andy and Matthew. They live in Pasadena. Steve recently watched all of “Star Trek” the remastered original season one on Amazon, so he has an inner nerd.